海底热液环境中嗜中性微需氧铁氧化菌的多样性、生物矿化作用及其代谢特征

铁元素是深海热液活动产物的主要成分之一，也是热液喷口处化能自养微生物生态系统的重要驱动元素。以Zetaproteobacteria为典型代表的嗜中性微需氧铁氧化菌是海底喷口及其周围环境中生物介导的Fe²⁺氧化这一生物矿化作用的主要驱动者。这些铁氧化菌通过氧化Fe²⁺获取维持自身代谢所必需的能量，同时分泌有机质将氧化后的不溶铁（氧化物或氢氧化物）沉淀于细胞外，形成具有螺旋丝带状、中空长杆状、分叉管状以及其他具有特殊形貌特征的显微结构体，进而堆积成广泛分布于海底的富铁氧化物/氢氧化物。越来越多的研究表明，编码细胞色素孔蛋白的cyc2基因是Zetaproteobacteria铁氧化菌进行Fe²⁺氧化的关键基因，而细胞色素c或其他周质细胞色素则是Fe²⁺氧化过程中的关键电子传递载体。基于宏基因组分析的系列研究揭示了Zetaproteobacteria普遍具有多种与氮、硫、氢以及砷元素循环密切相关的功能基因与代谢途径，暗示了其在上述元素循环过程中的潜在作用。本文系统地总结了海底热液喷口及其周围环境中发现的嗜中...

Diversity, biomineralization, and metabolic characteristics of neutrophilic microaerophilic iron-oxidizing bacteria in seafloor hydrothermal environments

Iron is one of the main components of deep-sea hydrothermal activity products and an important driving element for the chemoautotrophic microbial ecosystems at hydrothermal vents. The neutrophilic microaerophilic iron-oxidizing bacteria, represented by Zetaproteobacteria, are the main drivers of biomediated Fe²⁺ oxidation in hydrothermal vents and their surroundings. Iron-oxidizing bacteria acquires the energy essential to maintain their metabolism through Fe²⁺ oxidation, while secrete organic matter to precipitate the oxidized insoluble iron (oxides or hydroxides) outside the cells, forming microstructures with twisted stalks, hollow sheaths, branching hollow tubes or other special morphological features. These microstructures accumulate into iron-rich oxides/hydroxides widely distributed on the seafloor. Increasing studies have demonstrated that cyc2, encoding cytochrome-porin, is the key gene of Fe²⁺ oxidation by Zetaproteobacteria, while c-type cytochromes or other periplasmic cytochromes are the main electron transport carriers in Fe²⁺ oxidation. The metagenome-based studies reveal that Zetaproteobacteria generally possess multiple functional genes and metabolic pathways associated with nitrogen, sulfur, hydrogen, and arsenic cycling, suggesting the potential role of Zetaproteobacteria in the cycling of the above elements. In this paper, we systematically summarized the diversity, physiological characteristics, biomineralization-formed microstructure records, and key genes and electron transport pathways that mediated Fe²⁺ oxidation of neutrophilic microaerophilic iron-oxidizing bacteria in hydrothermal environments. This review facilitates the systematical understanding about the role of these microorganisms in the migration and enrichment of key ore-forming elements, the maintenance of ecological balance, and the mineralization by microorganisms in submarine hydrothermal vents.